Thermosetting powder paint composition

Abstract

A thermosetting powder paint composition for top coating excellent in weather resistance and storage stability, which comprising 100 parts by weight of an acrylic copolymer (A) having an epoxy group, and 0.01 to 2.0 parts by weight of an organic modified polysiloxane (B) containing at least one functional group, at least two silicon atoms and no radical-polymerizable unsaturated bond wherein the component (B) is contained in the condition that a part or all thereof has reacted and bonded with the component (A) or the component (C), or all thereof has not reacted with them.

What is claimed: 
     
       1. A thermosetting powder paint composition for top coating comprising: 100 parts by weight of an acrylic copolymer (A) obtained by polymerization in a reaction system containing a monomer (a1) having at least one radical-polymerizable unsaturated bond and at least one epoxy group in one molecule and a monomer (a2) having at least one radical-polymerizable unsaturated bond and no epoxy group in one molecule, and   0.01 to 2.0 parts by weight of an organic modified polysiloxane (B) having at least one functional group, at least two silicon atoms, and no radical-polymerizable unsaturated bond in one molecule,   wherein the component (B) is contained in the condition that a part or all thereof has reacted and bonded with the component (A) or all thereof has not reacted with the component (A).   
     
     
       2. The thermosetting powder paint composition according to claim 1, further comprising 5 to 60 parts by weight of a curing agent (C) composed of at least one polyvalent carboxylic acid-based compound selected from the group consisting of a polyvalent carboxylic acid (c1) and a polyvalent carboxylic anhydride (c2). 
     
     
       3. The thermosetting powder paint composition according to claim 2, wherein the functional group of the organic modified polysiloxane (B) is a group having reactivity to the acrylic copolymer (A) or the curing agent (C). 
     
     
       4. The thermosetting powder paint composition according to claim 2, wherein the component (B) is contained in the condition that a part or all thereof has reacted and bonded with the component (A) or the component (C). 
     
     
       5. The thermosetting powder paint composition according to claim 1, wherein the copponent (B) is contained in the condition that all thereof has not reacted with the other components. 
     
     
       6. The thermosetting powder paint composition according to claim 1, wherein the organic modified polysiloxane (B) includes at least one organic modified polysiloxane represented by any of the following general formulae (I), (II), (III) and (IV): ##STR7## wherein the formula (I), X 1  and X 2  are a group represented by any of the following general formulae (a) to (f) ##STR8## wherein formulae (a) to (f), Ra, Rb, Rc, Rd and Re represent a direct bond, alkylene group having 1 to 8 carbon atoms, phenylene group, alkylene group derivative, phenylene group derivative, or hydrocarbon group having an ether bond and/or ester bond, and Rf represents an alkyd group having 1 to 8 carbon atoms, phenyl group or derivative thereof, R 1  and R 2  represent a direct bond, alkylene group having 1 to 8 carbon atoms, phenylene group or derivative thereof, R 3  to R 8  represent an alkyl group having 1 to 8 carbon atoms, phenyl group or derivative thereof, and n1 represents a number from 1 to 1,500, ##STR9## wherein the formula (II), X 3  is a group represented by any of the above-described general formulae (a) to (e), R 9  to R 15  represent an alkyl group having 1 to 8 carbon atoms, phenyl group or derivative thereof, R 16  represents a direct bond, alkylene group having 1 to 8 carbon atoms, phenylene group, alkylene group derivative, phenylene group derivative, or hydrocarbon group having an ether bond and/or ester bond, and n2 represents a number from 1 to 1,500, ##STR10## wherein the formula (III), X 4  is a group represented by any of the above-described general formulae (a) to (e), R 17  to R 25  represent an alkyl group having 1 to 8 carbon atoms, phenyl group or derivative thereof, R 26  represents a direct bond, alkylene group having 1 to 8 carbon atoms, phenylene group, alkylene group derivative, phenylene group derivative, or hydrocarbon group having an ether bond and/or ester bond, x1 represent a number from 1 to 1,300, and y1 represents a number from 1 to 200, ##STR11## wherein the formula (IV), X 5 , X 6  and X 7  are a group represented by any of the above-described general formulae (a) to (e), R 30  to R 36  represent an alkyl group having 1 to 8 carbon atoms, phenyl group or derivative thereof, R 27  to R 29  represent a direct bond, alkylene group having 1 to 8 carbon atoms, phenylene group, alkylene group derivative, phenylene group derivative, or hydrocarbon group having an ether bond and/or ester bond, x2 represent a number from 1 to 1,300, and y2 represents a number from 1 to 200.   
     
     
       7. The thermosetting powder paint composition according to claim 1, wherein the organic modified polysiloxane (B) includes at least one organic modified polysiloxane represented by any of the following general formulae (V), (V'), (VI), (VI'), (VII), (VII'), (VIII), (VIII'), (IX), (X), (XI), (XII), (XIII), (XIV), (XV), (XVI), (XVII), (XVIII), (XIX), (XX), (XXI), (XXII), (XXIII), (XXIV), (XXV), (XXVI), (XXVII) and (XXVIII); ##STR12## wherein the formulae (V) to (XXVIII), R each independently represents a direct bond, alklene group having 1 to 20 carbon atoms, phenylene group, alklene group derivative, phenylene group derivative, or hydrocarbon group having an ether bond and/or ester bond, n each independently represents a number from 1 to 1,500, x each independently represents a number from 1 to 1, 300, and y each independently represents a number from 1 to 200. 
     
     
       8. The thermosetting powder paint composition according to claim 7, wherein the organic modified polysiloxane represented by any of the general formulae (V) to (XII) has an epoxy equivalent from 200 to 5,000. 
     
     
       9. The thermosetting powder paint composition according to claim 7, wherein the organic modified polysiloxane having a carboxyl group represented by any of the general formulae (XIII) to (XVI) has a carboxyl equivalent from 500 to 5,000. 
     
     
       10. The thermosetting powder paint composition according to claim 7, wherein the organic modified polysiloxane which is modified with phenol represented by any of the general formulae (XVII) to (XX) has a --OH equivalent from 1,000 to 5,000. 
     
     
       11. The thermosetting powder paint composition according to claim 7, wherein the organic modified polysiloxane having an amino group represented by any of the general formulae (XXI) to (XXVIII) has a --NH 2  equivalent from 500 to 10,000. 
     
     
       12. The thermosetting powder paint composition according to claim 1, wherein 0.01 to 1.0 parts by weight of the organic modified polysiloxane (B) is contained per 100 parts by weight of the acrylic copolymer (A). 
     
     
       13. The thermosetting powder paint composition according to claim 1, wherein the acrylic copolymer (A) is a copolymer obtained by polymerization in a reaction system containing 15 to 60 parts by weight of the monomer (a1) and 40 to 85 parts by weight of the monomer (a2) based on 100 parts by weight of the total weight of the monomer (a1) and the monomer (a2); and 40 to 85 parts by weight of the monomer (a2) contains 1 to 30 parts by weight of styrene and 39 to 55 parts by weight of a (meth)acrylate having a C1 to C12 alkyl group and/or cyclohexyl group. 
     
     
       14. The thermosetting powder paint composition according to claim 1, wherein the monomer (a1) includes at least one monomer selected from the group consisting of glycidyl (meth)acrylate and β-methylglycidyl (meth)acrylate. 
     
     
       15. The thermosetting powder paint composition according to claim 2, wherein the amount of the crosslinkable functional group in the curing agent (C) is from 0.5 to 1.5 equivalent per one equivalent of the epoxy group in the acrylic copolymer (A). 
     
     
       16. The thermosetting powder paint composition according to claim 15, wherein the melting point of the curing agent (C) is from 40 to 170° C. 
     
     
       17. The thermosetting powder paint composition according to claim 16, wherein the polyvalent carboxylic acid (c1) is an aliphatic dicarboxylic acid having 8 to 20 carbon atoms, the polyvalent carboxylic acid anhydride (c2) is a linear dimer or more, oligo or polyacidanhydride derived from dehydration condensation of an aliphatic dicarboxylic acid having 8 to 20 carbon atoms. 
     
     
       18. A method for producing a thermosetting powder paint using the composition of claim 1, which comprising the steps of: melting and kneading raw materials containing at least the acrylic copolymer (A), organic modified polysiloxane (B) and curing agent (C), and   cooling and grinding the melted and kneaded material.   
     
     
       19. The method for producing a thermosetting powder paint according to claim 18, wherein the melting and kneading step is conducted at a temperature from 40 to 130° C.